# The impedance of a circuit placed across a 120 V, 50 Hz (10 + j20). Find the current.

The impedance of a circuit placed across a 120 V, 50 Hz (10 + j20). Find the current.

### Right Answer is: 2.4 – j4.8)A

#### SOLUTION

Current in the circuit = Voltage / Load impedance

I = V/Z

$\begin{array}{l} \dfrac{{120}}{{10 + j20}}\\ \\ = \dfrac{{120}}{{10{\rm{\;}} + {\rm{\;}}j20}} \times \dfrac{{(10{\rm{\;}} – {\rm{\;}}j20)}}{{(10{\rm{\;}} – {\rm{\;}}j20)}}\\ \\ \dfrac{{(1200{\rm{\;}} – {\rm{\;}}j2400)}}{{100{\rm{\;}} + 400}}\\ \\ \dfrac{{12}}{5} – \dfrac{{24j}}{5} \end{array}$

I = 2.4 – j 4.8 A

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